RECENT ADVANCES IN SCIENCE 637 



explained by their possession of very rich coal and iron fields. 

 Germany has moreover the practical monopoly of the cheaply 

 mined, soluble potash salts so essential to agriculture. As 

 Upper Alsace contains the only well-proved potash deposits 

 which could possibly compete with the Stassfiirt supplies, the 

 regaining of Alsace by France would mean the collapse of the 

 present German monopoly. 



A shortage of glass-making material consequent upon the 

 war has resulted in a fortunate stimulation of the investigation 

 of British resources in glass-sands ; and Dr. P. G. H. Boswell 

 has just produced a memoir on the subject, which is published 

 at the instruction of the Ministry of Munitions by the Imperial 

 College of Science and Technology (Memoir on British Resources 

 of Sands suitable for Glass-making, 19 16, pp. 92). This work 

 includes excellent chapters on the nature, and methods of study, 

 of sands in general. It is shown that while very few British 

 sands equal the Fontainebleau or Lippe sands, especially in 

 extent or maintenance of sample, there are very large supplies 

 of material suitable for all but the finest grades of glass. It is 

 to be hoped that a further memoir on other refractory material, 

 especially moulding sands, will follow. A good account of 

 moulding sands is to be found in an article on " Admiralty 

 Gunmetal : Foundry Equipment," by H. S. Primrose (The 

 Metal Industry, 19 16, 8, 366). 



A second edition has appeared of the second volume of the 

 Special Reports on the Mineral Resources of Great Britain, 

 Barytes and Witherite, by the Geological Survey. The demand 

 for this economic work is gratifying, and should be an incentive 

 for the Survey to branch out in other fields of applied geology. 



Important work has recently been done on oil-shales, especi- 

 ally in the Scottish fields. In a paper on the origin of oil-shale 

 (Proc. Roy. Soc. Edin. 1916, 86,-44), Mr. E. H. Cunningham- 

 Craig discusses the question whether there is any essential 

 relationship between oil-rocks (impregnated with petroleum) 

 and oil-shales (petroleum obtained by distillation). He advances 

 the theory that oil-shale fields represent fossil oil-fields, in which 

 inspissated petroleum has been retained by absorption or 

 adsorption in colloidal clays, the petroleum being supplied 

 from the porous sands associated with the clays. In support of 

 this it is shown that the structural and stratigraphical relations 

 of oil-shale fields, as well as many other features, may often 



